Material handling for the insulating glass industry

ABSTRACT

Methods and apparatus for handling material for the insulating glass industry are disclosed. One method of handling material for the insulating glass industry in accordance with the present invention includes the step of arranging a plurality of bars into a plurality of stacks with adjacent stacks defining spaces dimensioned to receive a bar engaging member. The stacks of bars may then be transported to a desired destination. A bar engaging member may be inserted into a space defined by the stacks, and one or more bars may be grasped using the bar engaging member. A container for handling material for the insulating glass industry is also disclosed. The container may advantageously include a plurality of prearranged bar locating members configured to hold a predetermined type of bar stock.

RELATED APPLICATIONS

[0001] This application is related to and claims priority to U.S. patentapplication Ser. No. 60/262,807 by Trpkovski filed on Jan. 19, 2001 andthe entire disclosure of which is hereby incorporated by reference.

FIELD OF THE INVENTION

[0002] The present invention relates generally to methods and apparatusfor handling material for the insulating glass industry. Moreparticularly, the present invention relates to methods and apparatus forhandling elongate barstock that is useful for forming components suchas, for example, spacer frames and muntin bar lattices.

BACKGROUND OF THE INVENTION

[0003] Today, insulating glass units have achieved widespread use asbuilding components. In order to produce insulating glass unitsinexpensively and in high volume, modem manufacturing of insulatingglass units is often mechanized and/or automated. Various materials maybe used to manufacture insulating glass units, including sheets ofglass, spacer frames, and various sealants. Insulating glass units mayalso include muntin bars. Muntin bars may be used for both functionaland decorative purposes with glass windows or doors. The muntin bars areparticularly useful when they retain their geometric configuration anddo not separate, as well as when they are able to remain in a flatmating surface relation with the glass.

SUMMARY OF THE INVENTION

[0004] The present invention relates generally to methods and apparatusfor handling material for the insulating glass industry. Moreparticularly, the present invention relates to methods and apparatus forhandling elongate barstock that is useful for forming components suchas, for example, spacer frames and muntin bar lattices. One method ofhandling material for the insulating glass industry in accordance withthe present invention includes the step of arranging a plurality of barsinto a plurality of stacks with adjacent stacks defining spacesdimensioned to receive a bar engaging member. The stacks of bars maythen be transported to a desired destination. A bar engaging member maybe inserted into a space defined by the stacks, and one or more bars maybe grasped using the bar engaging member. In some implementations of theinvention, the step of grasping one or more bars using the first barengaging member includes the steps of inserting a second bar engagingmember into a second space defined by the stacks and trapping one ormore bars between the bar engaging member and the second bar engagingmember.

[0005] A container for handling material for the insulating glassindustry is also disclosed. In some implementations, the containerincludes a container frame and a plurality of combs selectively fixed tothe frame. In one aspect of the present invention, each comb includes aplurality of tines that are spaced to define a plurality of channelsdimensioned to accept bars having a predetermined width. In anotheraspect of the present invention, the tines are dimensioned to createspaces between adjacent channels, with each space being dimensioned toreceive a bar engaging member. In some implementations, each tinecomprises a shaft and a sleeve disposed over the shaft. The sleeve mayadvantageously comprise a no-mar material.

[0006] In some implementations, the present invention includes acontainer having a frame and a plurality of combs that are selectivelyfixed to the frame by a coupling mechanism. In some implementations, thecoupling mechanism comprises a plunger fixed to the frame of thecontainer and a detent defined by a base of the comb. The detent may beadvantageously dimensioned to accept at least a portion of the plunger.The plunger may comprise, for example, a ball and a spring arranged tobias the ball toward the detent.

[0007] In certain advantageous implementations, the present inventionutilizes a container including a first forklift interface and a secondforklift interface. In some implantations, each forklift interfacecomprises a first receptacle and a second receptacle. Each receptaclemay comprise, for example, a lumen defined by a tube. In someadvantageous implementations, each forklift interface comprises a firsttube positioned on a first side of a centroid of the container and asecond tube disposed on a second side of the centroid of the container.When this is the case, the first tube and the second tube may beadvantageously positioned substantially equidistantly from the centroidof the container.

[0008] A method of handling a first type of bars having a firstdimension and a second type of bars having a second dimension is alsodisclosed. In some implementations, this method includes the step ofproviding a container including a frame and a first set of combsselectively fixed to the frame. Each comb in the first set of combspreferably has a plurality of tines spaced to accept bars having thefirst dimension. The first set of combs may be removed from thecontainer and a second set of combs may be selectively fixed to theframe of the container. In certain implementations, each comb in thesecond set of combs advantageously has a plurality of tines spaced toaccept bars having the second dimension.

[0009] Another method in accordance with the present invention mayinclude the following steps:

[0010] 1) Providing a container having a plurality of prearranged muntinbar retaining channels configured to hold a predetermined type of bars.

[0011] 2) Placing a plurality of bars in the retaining channels of thecontainer.

[0012] 3) Placing a plurality of containers in a transportation vehicle.In some applications, the containers may be stacked in a semi trailer.

[0013] 4) Removing the containers from the transportation vehicle.

[0014] 5) Delivering at least one container to an arrival bay arrangedto receive a container.

[0015] 6) Sequentially removing bars from the container one at a time.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a flow chart illustrating a method of handling materialfor the insulating glass industry.

[0017]FIG. 2 is a perspective view of a container in accordance with thepresent invention.

[0018]FIG. 3 is a perspective view of an assembly including a vehicleand a plurality of containers that are disposed within the walls ofvehicle.

[0019]FIG. 4 is a plan view of an assembly including a semitrailer and aplurality of containers located within a plurality of walls ofsemitrailer.

[0020]FIG. 5 is a perspective view of a frame assembly in accordancewith an exemplary embodiment of the present invention.

[0021]FIG. 6 is an exploded perspective view of a portion of frameassembly of FIG. 5.

[0022]FIGS. 7 through 10 are cross sectional plan views of containers inaccordance with the present invention.

[0023]FIG. 11 is a perspective view of a system for automaticallyselecting and retrieving desired material from an appropriate container.

[0024]FIG. 12 is an additional perspective view a system of FIG. 11.

[0025]FIG. 13 is a cross sectional view of a container assembly inaccordance with the present invention.

[0026]FIG. 14 is an additional cross sectional view of the containerassembly of FIG. 13.

DETAILED DESCRIPTION

[0027] The following detailed description should be read with referenceto the drawings, in which like elements in different drawings arenumbered identically. The drawings, which are not necessarily to scale,depict selected embodiments and are not intended to limit the scope ofthe invention. Examples of constructions, materials, dimensions, andmanufacturing processes are provided for selected elements. All otherelements employ that which is known to those of skill in the field ofthe invention. Those skilled in the art will recognize that many of theexamples provided have suitable alternatives that can be utilized.

[0028]FIG. 1 is a flow chart 104 illustrating a method of handlingmaterial for the insulating glass industry. The material being handledmay comprise, for example, bar stock useful in the insulating glassindustry. Various types of bar stock may be used without deviating fromthe spirit and scope of the present invention. For example, bar stocksuitable for forming spacer frames useful in the insulating glassindustry may be used. By way of a second example, bar stock suitable forforming muntin bar lattices may also be used.

[0029] Bar stock used in the insulating glass industry often comprisesthin sheet metal (e.g., 4.5 mil stainless steel, 6.0 mil aluminum, andthe like). This thin sheet metal can be easily damaged during handling.For example, the bar stock may be scratched, bent and/or dented. Sometypes of bar stock may include a finish such as, for example, paint.This finish may be particularly susceptible to scratching.

[0030] Block 106A of flow chart 104 comprises the step of providing acontainer. The container may be provided, for example, proximate asource of bar stock. This source of bar stock may be, for example, afactory where bar stock is fabricated. In a preferred method inaccordance with the present invention, the container includes aplurality of prearranged bar locating members configured to hold apredetermined type of bar stock. In some methods in accordance with thepresent, the container is provided at a location where bar stock isbeing fabricated and the bar stock is placed in the container soon afterbeing fabricated. Placing the bar stock in the contained soon after itis fabricated reduces the likelihood that the bar stock will be damaged.

[0031] In one exemplary embodiment, the bar locating members comprisetines which include a no-mar sleeve. The no-mar sleeve may reduce thelikelihood that the outer surface of the bar stock is scratched duringhandling.

[0032] Block 106B of flow chart 104 comprises the step of loading thecontainer. The step of loading the container may involve placing aplurality of bars between the bar locating members of the container.This step may also involve arranging a plurality of bars into aplurality of stacks with adjacent stacks defining spaces dimensioned toreceive a bar engaging member.

[0033] Block 106C of flow chart 104 comprises the step of transportingthe container. The step of transporting the container may involveplacing a plurality of containers in a transportation vehicle. In someapplications, the containers may be arranged in an interlocking fashionin the vehicle. The step of transporting the container may also involveremoving the plurality of containers from the transportation vehicle.The step of transporting the container may also involve delivering atleast one container to an arrival bay arranged to receive the container.The container may be delivered to the arrival bay using a vehicle, forexample, a fork lift.

[0034] Block 106D of flow chart 104 comprises the step of inserting abar engaging member into a space defined by adjacent stacks of barstock. Various bar engaging members may be utilized without deviatingfrom the spirit and scope of the present invention. Bar engaging memberssuitable for some applications may comprise, for example, grippers,pinchers, fingers, and vacuum cups.

[0035] Block 106E of flow chart 104 comprises the step of removing barstock from the container. In some methods in accordance with the presentinvention, bar stock is removed one piece at a time. In other methods inaccordance with the present invention, a plurality of pieces of barstock are grasped and removed from the container.

[0036] Block 106F comprises the step of returning the container. Thecontainer may be returned, for example, to the bar stock source. At thebar stock source, the container may by reloaded by placing a pluralityof bars between the bar locating members of the container.

[0037]FIG. 2 is a perspective view of a container 100 in accordance withthe present invention. Container 100 of FIG. 2 includes a plurality ofpre-arranged bar locating members 108 dimensioned and spaced for holdingand dispensing a desired type of bar stock. Container 100 of FIG. 2 alsoincludes a first forklift interface 120A and a second fork liftinterface 120B. First forklift interface 120A comprises a plurality ofreceptacles 124A that are preferably dimensioned to receive the forks ofa forklift. In the embodiment of FIG. 2, each receptacle 124A comprisesa lumen 122A defined by a beam 126. Second forklift interface 120Bcomprises a plurality of receptacles 124B that are also preferablydimensioned to receive the forks of a forklift. In the embodiment ofFIG. 2, each receptacle 124B comprises a lumen 122B defined by a crossmember 128. As shown in FIG. 2, each lumen 122A has a central axis 123Aand each lumen 122B has a central axis 123B. In a preferred embodiment,the forks of a fork lift maybe inserted into either end of lumens 122A,122B.

[0038] Container 100 has longitudinal axis 101 and a lateral axis 103that intersect at a centroid 168 of container 100. In the embodiment ofFIG. 2, beams 126 and cross members 128 both comprise lengths of tubinghaving a generally rectangular cross section. In FIG. 2, it may beappreciated that each forklift interface comprises a first tubepositioned on a first side of centroid 168 of container 100 and a secondtube disposed on a second side of centroid 168 of container 100. In theembodiment of FIG. 2, the first tube and the second tube of eachforklift interface are positioned substantially equidistantly fromcentroid 168 of container 100.

[0039] In FIG. 2 it may be appreciated that first forklift interface120A and a second fork lift interface 120B are disposed at an anglerelative to one another. In the embodiment of FIG. 2, each cross member128 is arranged at about a 90 degree angle relative to each beam 126.

[0040] In FIG. 2, it may be appreciated that container 100 includes aplurality of first mating elements 130 and second mating elements 132.In the embodiment of FIG. 2 each first mating element 130 comprises apost 134 and each second mating element 136 comprises a socket 138. Insome embodiments of the present invention, sockets 140 are dimensionedand located to accept the posts 142 of a second substantially similarcontainer.

[0041]FIG. 3 is a perspective view of an assembly including a vehicle144 and a plurality of containers 25 that are disposed within the walls74 of vehicle 144. In some methods in accordance with the presentinvention, a plurality of containers 25 are mated with one another in aninterlocking stacked configuration. In the embodiment of FIG. 3, vehicle144 comprises a semitrailer 150. It is to be appreciated that acontainer may be transported using various vehicles without deviatingfrom the spirit and scope of the present invention. Examples of vehicleswhich may be suitable in some applications include trucks, airplanes,ships, trains, and fork lifts.

[0042]FIG. 4 is a plan view of an assembly including a semitrailer 150and a plurality of containers 25 located within a plurality of walls 74of semitrailer 150.

[0043]FIG. 5 is a perspective view of a frame assembly 152 in accordancewith an exemplary embodiment of the present invention. Frame assembly152 includes a frame 154 and a plurality of combs 156 that areselectively coupled to frame 154. Each comb 156 of frame assembly 152comprises a base 158 and a plurality of tines 160 extending away fromthe base 158. Frame 154 of frame assembly 152 includes a plurality ofbeams 126 and a plurality of cross members 128 fixed to beams 126, forexample by welding.

[0044] First forklift interface 120A comprises a plurality ofreceptacles 124A that are preferably dimensioned to receive the forks ofa forklift. In the embodiment of FIG. 2, each receptacle 124A comprisesa lumen 122A defined by a beam 126. Second forklift interface 120Bcomprises a plurality of receptacles 124B that are also preferablydimensioned to receive the forks of a forklift. In the embodiment ofFIG. 2, each receptacle 124B comprises a lumen 122B defined by a crossmember 128. As shown in FIG. 2, each lumen 122A has a central axis 123Aand each lumen 122B has a central axis 123B. In a preferred embodiment,the forks of a fork lift maybe inserted into either end of lumens 122A,122B.

[0045] Frame 154 has longitudinal axis 125 and a lateral axis 127 thatintersect at a centroid 168 of frame 154. In the embodiment of FIG. 5,beams 126 and cross members 128 both comprise lengths of tubing having agenerally rectangular cross section. In FIG. 5, it may be appreciatedthat each forklift interface comprises a first tube positioned on afirst side of a centroid of the container and a second tube disposed ona second side of the centroid of the container. In the embodiment ofFIG. 5, the first tube and the second tube of each forklift interfaceare positioned substantially equidistantly from the centroid of thecontainer.

[0046] In FIG. 5 it may be appreciated that first forklift interface120A and a second fork lift interface 120B are generally orthogonal toone another. In the embodiment of FIG. 5, each cross member 128 isarranged at about a 90 degree angle relative to each beam 126.

[0047]FIG. 6 is an exploded perspective view of a portion of frameassembly 152 of FIG. 5. In the embodiment of FIG. 6, one comb 156 isshown in a detached position. In some embodiments of the presentinvention, combs 156 are selectively coupled to frame 154 by a couplingmechanism 174. In the embodiment of FIG. 6, coupling mechanism 174comprises a plunger 176 that is fixed to frame 154 and a detent 178defined by base 158 of comb 156. Detent 178 is preferably dimensioned toaccept at least a portion of plunger 176. Plunger 176 may comprise, forexample, a ball and a spring that is arranged to bias the ball towarddetent 178.

[0048] In FIG. 6, it may be appreciated that each tine 180 includes ashaft 182 and a sleeve 184 that is disposed about shaft 182. In apreferred embodiment, each sleeve 184 comprises a no-mar material thatis selected to avoid damaging, marking, or causing blemishes on a barstock material. Various no-mar materials may be used without deviatingfrom the spirit and scope of the present invention. Examples of no-marmaterials which may be suitable in some applications include polymericmaterials (e.g., polyethylene and polypropylene) and elastomericmaterials (e.g., polyurethane). It is to be appreciated that a containerin accordance with the present invention may be configured to carry adesired type of bar stock by installing combs having tines that aredimensioned and spaced to receive the desired bar stock.

[0049]FIGS. 7 through 10 are cross sectional plan views of containers100 in accordance with the present invention. Each container 100includes a plurality bar locating members 108 that are preferrablydimensioned and spaced for receiving desired pre-sized bars 188. InFIGS. 7 through 10, it may be appreciated that bar locating members 108are spaced to define a plurality of channels 162 dimensioned to acceptbars having a given width. In the embodiments illustrated in FIGS. 7through 10, a stack 228 of bars 188 is disposed within each channel 162.Also in FIGS. 7 through 10, it may be appreciated that bar locatingmembers 108 are dimensioned to create spaces 164 between adjacentchannels 162. In a preferred embodiment, each space 164 is dimensionedto receive a bar engaging member. In this preferred embodiment, eachspace 164 has dimensions suitable to allow access of a portion of aselection and retrieval subsystem to automatically select and retrievebars 188 from the container, and deliver the bars to a desired location.The containers 100 illustrated in FIGS. 7 through 10 also include aplurality of casters 252. Casters 252 may facilitate movement of thecontainers. Containers may include, for example, casters, rollers, andwheels without deviating from the spirit and scope of the presentinvention.

[0050]FIG. 11 is a perspective view of a system 192 for automaticallyselecting and retrieving desired material from an appropriate container.System 192 includes a plurality of bays 194. Each bay 194 is preferablyconfigured to receive a container. In the embodiment of FIG. 11, eachbay 194 includes a plurality of alignment pins 198.

[0051] System 192 also includes an bar engaging assembly 200 that iscoupled to a motion control system 196. In the embodiment of FIG. 11,bar engaging assembly 200 includes a plurality of bar engaging members202. In some embodiments of the present invention, two or more barengaging members 202 may be selectively urged towards one another totrap one or more bars. The force used to urge two or more bar engagingmembers 202 towards one another may be provided by, for example, one ormore air cylinders.

[0052] In the embodiment of FIG. 11, motion control system 196 includesa z-axis linear actuator 204, an x-axis linear actuator 206 and aplurality of y-axis linear actuators 208. In a preferred embodiment,motion control system 196 is capable of selectively placing bar engagingassembly 200 in a desired position. Motion control system 196 maycomprise various elements without deviating from the spirit and scope ofthe present invention. For example, motion control system 196 maycomprise one or more robots, one or more linear actuators, and/or one ormore rotary actuators. Linear actuators which may be suitable in someapplications are commercially available from Lintech Corporation ofMonrovia, Calif. and Tol-o-matic Corporation of Hamel, Minn.

[0053] System 192 also includes a conveyor 220 that preferably extendsthrough at least a portion of system 192. In some methods in accordancewith the present invention, conveyor 220 may be utilized to transportmaterial from system 192 to a desired location. In the embodiment ofFIG. 11, conveyor 220 includes a belt 222 and a plurality of rollers224. Bar engaging assembly 200 and motion control system 196 may be usedto retrieve bars and place them on belt 222 of conveyor 220.

[0054]FIG. 12 is an additional perspective view of system 192 of FIG.11. In the embodiment of FIG. 12, a container 100 has been positioned ineach bay 194. For purposes of illustration, a portion of each container100 is cut-away to reveal an alignment pin 198. Thus, in FIG. 12, it maybe appreciated that each container 100 includes a plurality of sockets140 that are dimensioned to receive an alignment pin 198. In somemethods in accordance with the present invention, alignment pins 198 maybe used to locate containers 100 relative to system 192.

[0055] In the embodiment of FIG. 12, each container 100 holds aplurality of bar stock stacks 228 which are illustrated somewhatdiagramatically in FIG. 12. In some embodiments, each stack 228comprises a plurality of bars 230 arranged one on top of the other. Onebar 230 shown held by bar engaging members 202 of bar engaging assembly200. Bar engaging assembly 200 and motion control system 196 may be usedto select a container 100 containing a plurality of desired bars, removea desired bar, and place the desired bar on belt 222 of conveyor 220. InFIG. 12, one bar 230 can be seen resting on belt 222 of conveyor 220.

[0056]FIG. 13 is a cross sectional view of a container assembly 234 inaccordance with the present invention. Container assembly 234 includes acontainer 100 having a plurality of bar locating members 108. Aplurality of bars 230 are disposed between adjacent bar locating members108 to form stacks 228. In FIG. 13, a first bar engaging member 202A canbe seen disposed within a first space 164A defined by a plurality ofbars 230. A second bar engaging member 202B is disposed in a secondspace 164B defined by a plurality of bars 230. In the embodiment of FIG.13, first bar engaging member 202A and second bar engaging member 202Bhave been urged towards one another, and a bar 230 has been capturedbetween first bar engaging member 202A and second bar engaging member202B.

[0057]FIG. 14 is an additional cross sectional view of the containerassembly 234 of FIG. 13. In the embodiment of FIG. 14, first barengaging member 202A and second bar engaging member 202B have been movedto a new position, for example, using motion control system 196. In FIG.14, it may be appreciated that a bar 230 has been lifted from container100 by first bar engaging member 202A and second bar engaging member202B.

[0058] Numerous characteristics and advantages of the invention coveredby this document have been set forth in the foregoing description. Itwill be understood, however, that this disclosure is, in many respects,only illustrative. Changes may be made in details, particularly inmatters of shape, size and ordering of steps without exceeding the scopeof the invention. The invention's scope is, of course, defined in thelanguage in which the appended claims are expressed.

What is claimed is:
 1. A method of handling material for the insulatingglass industry, comprising the steps of: arranging a plurality of barsinto a plurality of stacks with adjacent stacks defining spacesdimensioned to receive a bar engaging member; transporting the bars to adesired destination; inserting the bar engaging member into a spacedefined by the stacks; and grasping at least one bar using the barengaging member.
 2. The method of claim 1, wherein the step of graspingat least one bar using the first bar engaging member includes the stepsof; inserting a second bar engaging member into a second space definedby the stacks; and trapping at least one bar between the bar engagingmember and the second bar engaging member.
 3. The method of claim 1,further including the step of lifting at least one bar using the barengaging member.
 4. The method of claim 1, wherein each stack comprisesa plurality of bars arranged one on top of the other.
 5. The method ofclaim 1, further including the step of providing a container having aplurality of prearranged bar locating members.
 6. The method of claim 5,wherein the step of arranging the bars includes the step of placing thebars between adjacent bar locating members.
 7. The method of claim 5,wherein the step of transporting the bars to the desired destinationincludes the step of placing the container inside a vehicle.
 8. Themethod of claim 5, further including the step of mating the containerwith a second container.
 9. The method of claim 8, wherein the step ofmating the container with the second container includes the step ofinserting a male mating member of one of the containers into a femalemating member of another of the containers.
 10. The method of claim 8,wherein the second container is substantially identical to thecontainer.
 11. The method of claim 1, wherein the step of transportingthe container to the desired destination includes the step of locatingthe carrier relative to a robot.
 12. The method of claim 11, wherein thecontainer comprises a plurality of alignment sockets; and the step oflocating the container relative to the robot includes the step of matingthe alignment sockets with a plurality of alignment pins.
 13. The methodof claim 12, wherein each alignment pin is located a predetermineddistance from the robot.
 14. A container for handling material for theinsulating glass industry, comprising: a container frame; a plurality ofcombs selectively fixed to the frame; each comb including a plurality oftines; the tines being spaced to define a plurality of channelsdimensioned to accept bars having a predetermined width; the tines beingdimensioned to create spaces between adjacent channels; and each spacebeing dimensioned to receive a bar engaging member.
 15. The container ofclaim 14, wherein each tine comprises a shaft and a sleeve disposed overthe shaft.
 16. The container of claim 15, wherein the sleeve comprises apolymeric material.
 17. The container of claim 16, wherein the polymericmaterial comprises polyethylene.
 18. The container of claim 15, whereinthe sleeve comprises an elastomeric material.
 19. The container of claim18, wherein the elastomeric material comprises polyurethane.
 20. Thecontainer of claim 14, wherein each comb is selectively fixed to theframe by a coupling mechanism.
 21. The container of claim 20, whereinthe coupling mechanism comprises a plunger fixed to one of the frame andthe comb, and a detent defined by the other of the frame and the comb;and the detent being dimensioned to accept at least a portion of theplunger.
 22. The container of claim 21, wherein the plunger comprises aball and a spring arranged to bias the ball toward the detent.
 23. Thecontainer of claim 1, further including a first forklift interface and asecond forklift interface.
 24. The container of claim 23, wherein eachforklift interface comprises a first receptacle and a second receptacle.25. The container of claim 24, wherein each receptacle comprises a lumendefined by a tube.
 26. The container of claim 25, wherein each forkliftinterface comprises a first tube positioned on a first side of acentroid of the container and a second tube disposed on a second side ofthe centroid of the container.
 27. The container of claim 26, whereinthe first tube and the second tube are positioned substantiallyequidistantly from the centroid of the container.
 28. The container ofclaim 25, where in the lumens of the second forklift interface aredisposed at an angle relative to the lumens of the first forkliftinterface.
 29. The container of claim 28, wherein the angle is about a90 degree angle.
 30. A method of handling a first type of bars having afirst dimension and a second type of bars having a second dimension,comprising the steps of: providing a container including a frame and afirst set of combs selectively fixed to the frame; each comb in thefirst set of combs having a plurality of tines spaced to accept barshaving the first dimension; removing the first set of combs from thecontainer; and selectively fixing a second set of combs to the frame ofthe container.
 31. The method of claim 30, wherein each comb in thesecond set of combs has a plurality of tines spaced to accept barshaving the second dimension.